Table 1.

Calibration points used for relaxed Bayesian molecular clock analyses

Split	Bounds		Strata	Fossils	Reference
	Max	Min
Euchelicerata-Pycnogonida	543	501	lower bound: first arthropods in the Early Cambrian upper bound: base of Upper Cambrian	Rusophycus; Cambropycnogon klausmuelleri	Benton 1993 [41], Crimes 1987 [45], Waloszek and Dunlop 2002 [46]
origin of Xiphosura		445	Late Ordovician	Lunataspis aurora	Rudkin et al. 2008 [47]
origin of Scorpiones		428	Silurian	Allopalaeophonus caledonicus	Dunlop 2010 [43]
Mygalomorphae-Araneaomorphae	382.7	240	lower bound: Grès à meules, upper Buntsandstein, Trias; upper bound: Givetian, middle Devonian	Rosamygale grauvogeli; Attercopus fimbriunguis	Selden and Gall 1992 [48], Selden et al. 2008 [49]